45_9Aug_Magic Squares In Grid.cpp

class Solution {
public:
    bool isMagicGrid(vector<vector<int>>& grid, int r, int c) {
        // uniqueness 1 to 9 and distinct
        unordered_set<int> st;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                int num = grid[r + i][c + j];
                if (num < 1 || num > 9 || st.count(num)) {
                    return false;
                } else {
                    st.insert(num);
                }
            }
        }

        // check Sum - Rows and columns
        int SUM = grid[r][c] + grid[r][c + 1] + grid[r][c + 2];
        for (int i = 0; i < 3; i++) {
            if (grid[r + i][c] + grid[r + i][c + 1] + grid[r + i][c + 2] !=
                SUM) {
                return false;
            }

            if (grid[r][c + i] + grid[r + 1][c + i] + grid[r + 2][c + i] !=
                SUM) {
                return false;
            }
        }

        // diaornal and anti-diagonal
        if (grid[r][c] + grid[r + 1][c + 1] + grid[r + 2][c + 2] != SUM) {
            return false;
        }

        if (grid[r][c + 2] + grid[r + 1][c + 1] + grid[r + 2][c] != SUM) {
            return false;
        }

        return true;
    }

    int numMagicSquaresInside(vector<vector<int>>& grid) {
        int rows = grid.size();
        int cols = grid[0].size();

        int count = 0;

        for (int i = 0; i <= rows - 3; i++) {
            for (int j = 0; j <= cols - 3; j++) {
                if (isMagicGrid(grid, i, j)) {
                    count++;
                }
            }
        }

        return count;
    }
};